The defence secretary, Des Browne, yesterday strongly hinted he would join other senior ministers in supporting the retention of a British independent nuclear deterrent. He highlighted "the terrifying prospect" of a state with nuclear weapons linking up with a terrorist group.

He promised an open debate but said: "There has been significant leakage from the North Koreans' nuclear development. We will need to look into what we know about non-state actors such as al-Qaida who are playing a significant and dangerous role in the future of our security."

He said the government would publish a white paper this year setting out its views on the deterrent, but would not rule in or out whether MPs would vote on the final decision. He suggested that one possibility was to extend the life of the existing system.

His comments came as a former Labour defence secretary, Denis Healey, said there was no military justification for keeping Britain's nuclear deterrent. Lord Healey, who played a key role in maintaining the Polaris nuclear weapons systems in the 1960s, said the only reason for maintaining the deterrent was "political", to bolster Britain's influence abroad.

"Nuclear weapons are infinitely less important in our foreign policy than they were in the days of the cold war. I don't think we need nuclear weapons any longer," he told BBC News 24's Straight Talk. "I think the military case now for nuclear weapons has gone."

In answer to a parliamentary question yesterday Mr Browne made clear that MPs would only be consulted on the future of Britain's nuclear deterrent after ministers had come to a decision. A decision would be taken before the end of the year. However, he refused to disclose how much had been spent developing new arming and firing systems for the Trident nuclear warhead, on grounds of national security.

Nick Harvey, the Lib Dem spokesman who raised the question, said Mr Browne's answers "make a mockery of the prime minister's promise to hold the 'fullest possible parliamentary debate' on Trident".

He added: "Refusal to comment on warhead design work at Aldermaston appears to be further evidence of an intention to suppress debate."